This invention relates to light weight abrasive tumbling media for use in mass industrial finishing operations and to methods of making same. More particularly, this invention relates to the production of ceramic tumbling media consisting of discrete abrasive particles of essentially uniform size and shape which exhibit a final bulk density after firing below 65 lbs/ft..sup.3.
Abrasive tumbling media have long been used in mass industrial finishing operations for refining the surfaces of metallic and plastic parts. Such media have customarily included discrete abrasive particles of various sizes and shapes made from ceramics, porcelains, natural or synthetic stone, clay, and plastics. Conventional ceramic tumbling media exhibit a bulk density of 80 to 120 lbs/ft..sup.3 which can damage delicate parts during mass finishing operations. Plastic tumbling media having a significantly lower bulk density have commonly been used for such operations, but plastic gives off an undesirable effluent during production which is harmful to the environment and which may require treatment as a hazardous waste. Accordingly, there exists a need for improved light weight, low density ceramic tumbling media the production or use of which is not detrimental to the environment.
Such a light weight abrasive is for example described in U.S. Pat. No. 5,049,166. That light weight media is formed by using a gas generating material during processing. While the material described in the above patent is a vast improvement over previous materials, it still has certain disadvantages. In particular media wear is much higher than desired. Quantity of cut per unit weight is not as high as desired and porosity is higher than desired.